Resolve Invalid MIME content

Problem:

When you migrate to Exchange or Office 365 by using EdbMails Exchange migration or Office 365 Migration software, you may encounter one of the following errors in the EdbMails log report.

Error while uploading package. System.Exception: [ErrorMimeContentInvalidBase64String] - Invalid base64 string for MIME content.

Error while uploading package. System.Exception: [ErrorMimeContentInvalid] - Invalid MIME content.

Resolution:

The invalid MIME content indicates that the mail items are corrupted. This error normally occurs when the properties of the items that are necessary for migration are either missing or broken although you can access them in Outlook or OWA. The destination MS Exchange Server EWS service requires that the migrated items are in a healthy state and rejects them if the items are corrupted.

MS Outlook can repair damaged files and items if the issue only affects a small number of these items and mailboxes.

Steps to resolve invalid MIME contents using MS Outlook

1. Create a temporary storage location on your computer for files with the damaged MIME content
2. Launch Microsoft Outlook.
3. Check your mailbox for the damaged mails. Most likely, you can open them in Microsoft Outlook without any problems. To identify the corrupted items, check the EdbMails log files first
4. Copy the corrupted items from MS Outlook into the temporary folder you created in step 1
5. From Microsoft Outlook, remove the damaged items permanently. To remove such items, select them from your mailbox and press 'Shift+Delete'
6. Drag the items from the temporary folder (See step 4) into MS Outlook. While performing this step, make sure to copy the items into the same mailbox folder from which they were originally taken.
7. Wait a couple of minutes to synchronize Outlook with the Exchange Server
8. Close Microsoft Outlook and perform the migration with EdbMails

If the preceding steps do not assist or there are too many corrupted items, you can exclude such items from the migration using the 'Settings' option in EdbMails Migration window.